1. Field of the Invention
The invention herein relates to fluid dispensing devices. More particularly it relates to small, portable fluid dispensing devices, including devices used to dispense metered quantities of liquid medication to ambulatory patients and devices to disperse vapors into the surrounding environment.
2. Description of the Prior Art
In recent years there have been numerous applications for small, easily portable liquid and other fluid dispensers. A major application for instance, is in the medical and veterinary fields, where ambulatory patients, whether human or animal, can wear or carry such devices which are used to administer medication to them on an ongoing or extended basis.
Another use of such devices is to provide for dispersion of gases or vapors into the ambient environment. Typical for instance, are the small vapor dispensing devices used in homes and offices to provide either a pleasant scent or to mask or eliminate undesirable odors.
Many of the previous devices have been single use products. The devices supplied with a sufficient quantity of a propellant to force the liquid in the reservoir to be ejected from the device over a predetermined time period. Once the quantity of liquid is dispensed, the propellant is substantially used up and the device is simply discarded. Successful attempts to reuse such devices by refilling and recharging have been of only limited success, since the difficulty of such refilling and recharging is usually sufficiently great that it is more economical to discard the device and simply provide a new device with a new quantity of liquid and a new propellant charge.
A number of small portable electrochemical dispensing devices have previously been developed which can continually dispense liquid at preset or controllable rates. The devices use novel electrochemical pumps which have been the subject of prior United States patents, including U.S. Pat. No. 4,902,278 to co-applicant Maget entitled "FLUID DELIVERY MICROPUMP," in which electrochemistry and membrane technology is used to reduce oxygen in air on one side of a water-containing electrolytic cell and oxidize oxygen from the water on the opposite side to generate molecular oxygen, with the molecular oxygen so generated being used as the propellant to force liquid from an adjacent reservoir. A variety of different types of devices have been developed and patented and others are the subject of pending patent applications. All of these devices however, have either been single unit devices in which the pumping mechanism was integral with the reservoir structure or, for those devices where the pumping mechanism was separable from the liquid or gas reservoir portion, the devices have been such that the coupling between the two portions was rudimentary and the devices were not designed for more than limited portability.